Hi Larry, I use redline gas additive. If used at a rate of 15oz per 100gals on a ongoing basis it costs about 4 cents per gallon. If the whole bottle (15oz) is used as one time clean up, every 100gals then it is still 4 cents per gallon. I use it in my C230 and the wifes' Subaru and we get mileage in excess of EPA calculations for both city and country. In the C230, I burn Mid grade unleaded and have not observed any pinging when I add to each tank at the rate of 1.5oz per 10gals Roger